Device for the temperature equalisation of coating media

ABSTRACT

Temperature control of the coating medium is performed to influence the processability of coating media in an applicator system. In order to operate without losing efficiency, devices acting directly from the inside or the outside for heat supply or dissipation are connected to the elements guiding the coating medium. The temperature of the coating medium is influenced by measuring the temperature within the coating medium and, if necessary, at the elements guiding the coating medium.

FIELD OF THE INVENTION

The invention pertains to a device for temperature control of coatingmediums used in printing machines.

BACKGROUND OF THE INVENTION

In applicator systems for printing presses, e.g., in coating systems, itis known to regulate the viscosity of the coating medium by means oftemperature control. Temperature control can be used to regulate theprocessability of coating media for different types of media and fordifferent methods of application. This can expand the processing rangeof such an applicator system.

A known device for coating surfaces in a printing process is disclosedin U.S. Pat. No. 5,520,739 A. This reference indicates that a coatingcomposition for different systems can be supplied from a single storagecontainer for the feeding of coating compositions to printing processes.Each device for supplying the coating composition is described as areactor vessel, in which the temperature, and thus also the viscosity,of the coating composition can be influenced. For this purpose, there isa heat exchanger and a temperature sensor, as well as a viscometer fordetermining the viscosity of the coating composition in the reactorvessel.

The described device has the disadvantage that the coating compositioncan only be affected or controlled before the actual printing process orcoating process. On the way between the reactor vessel and the printingprocess, however, the physical properties of the coating composition canchange.

Another disadvantage of the above described device is that not all ofthe processing sequences can be affected by the processing sequences oftemperature control. It is commonly necessary for there to be processingsequences for the rinsing or cleaning of the applicator system and theelements contained therein that transport the coating composition inorder to prevent permanent contamination through hardening of thecoating composition. Here, it is also advantageous to control thetemperature of the cleaning process. This is not possible with thedescribed device.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object invention is to provide a coating system for a printingpress in which the temperature of the coating medium is more reliablycontrolled in close proximity to the printing process and in which thecleaning process following a coating operation also may be temperaturecontrolled for optimum processing.

In carrying out the invention, it is advantageous if the temperaturecontrol of the coating composition is not performed in a storagecontainer, but instead directly at the place of processing. Suitablepositions or locations for temperature control include a chamber wiper,a screen roller connected to the chamber wiper, or, if necessary, ametering roller connected to the screen roller or to a comparableapplicator roller. It also is advantageous if the form cylindertransferring the coating layer or the coating medium is a devicesusceptible temperature control. In one suitable form of the invention,a heat exchanger is provided within each roller or chamber wiper. Inanother form of the invention, the temperature is detected at eachelement transmitting the coating medium.

In carrying out the invention, it is advantageous if the temperaturecontrol of the coating composition is no longer performed in a storagecontainer, but instead directly at the place of processing. Suitablepositions for temperature control are a chamber wiper, a screen rollerconnected to the chamber wiper, or, if necessary, a metering rollerconnected to the screen roller or to a comparable applicator roller. Itis also advantageous if the form cylinder transferring the coating layeror the coating medium is realized as a device for temperature control.In a suitable form, there can be a heat exchanger within each roller orchamber wiper. In an additional suitable form, the temperature isdetected at each element transmitting the coating medium.

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is side elevational view of a printing machine having anapplicator system with a temperature control in accordance with theinvention.

While the invention is susceptible of various modifications andalternative constructions, a certain illustrative embodiment thereof hasbeen shown in the drawings and will be described below in detail. Itshould be understood, however, that there is no intention to limit theinvention to the specific form disclosed, but on the contrary, theintention is to In re Appln. of Scholzig et al. cover all modifications,alternative constructions, and equivalents falling within the spirit andscope of the invention.

Referring now more particularly to the drawings, there is shown anillustrative printing machine having a coating medium applicator systemin accordance with the invention. The applicator system includes aprinting cylinder 1 for guiding a sheet to be coated, a form cylinder 2for transferring a layer of the coating medium to the sheet to beprinted, and a metering system 5 for generating the coating. In thiscase, the metering system 5 comprises an applicator roller in the formof a screen roller 3 having uniformly arranged cups about the peripheryfor transport of the coating medium. A chamber wiper 4 associated withthe screen roller has two wipers, which together with the body of thechamber wiper, define a space for feeding the coating medium. Thechamber wiper 4 is set with its two wipers against the screen roller 3and transfers the coating medium into the recesses of the screen roller3, with the coating medium being supplied to the chamber wiper by meansof a pump. The coating medium is released when the screen roller 3 rollsonto the surface of the form cylinder 2, which has a printing formattached thereto. The printing form can a uniform surface that coats theentire printing area of a printing sheet, or it can be adopted forcoating only parts of the printing sheet.

In accordance with an important aspect of the invention, the coatingsystem is provided with temperature control devices for ensuring uniformprocessing of a wide possible range of coating media. To this end, inthe illustrated embodiment, a heat enlarger A is mounted in the regionof the chamber wiper 4. The heat-exchanger device A, which can be of aknown type preferably is inserted into or attached to the wiper body.This allows the wiper body, including the wipers connected to the body,to be maintained at a predetermined temperature which, in turn, heatsthe coating medium in the chamber wiper 4 to a predeterminedtemperature. Thus, the coating medium may be continuously maintained atthe preselected temperature. For this purpose, a temperature sensor canbe provided in the chamber wiper 4 that continuously detects thetemperature of the chamber wiper 4. Furthermore, a temperature sensorcan be provided in the chamber wiper 4 that continuously detects thetemperature of the coating medium. An arrangement with two sensors canprovide permanent equalization. A controller guarantees that, ifnecessary, there is a sufficiently large temperature difference betweenthe wiper body and the supplied coating medium so that for theprocessing the coating medium has the desired temperature adjusted forviscosity and transfer properties, as well as, if necessary, for dryingproperties.

Furthermore, the screen roller 3 can have a temperature-control device Bknown for inking systems of rotary printing presses. For this purpose, aseries of flow channels that carry a temperature-controlled fluid in twodirections can be formed in the screen roller 3. The flow channels arearranged such that the temperature-controlled fluid flows in one channeltowards the screen roller 3 and in an adjacent channel, the fluid flowsback in the opposite direction. In this way, the temperature-controlfluid can be input and then removed from one side of the screen roller3.

Another possible temperature-control method consists in providing theform cylinder 2 with a temperature-control device C like those known forscreen rollers. For this purpose, there are also flow channels in theform cylinder 2 that can carry a temperature-controlled fluid.

Alternatively, for coating by means of a chamber wiper and a screenroller, there can also be a roller coating system. This roller coatingsystem comprises, e.g., two rollers, of which one is the applicatorroller corresponding to screen roller 3, and the second is a meteringroller at the position of the chamber wiper 4. The coating medium is fedinto a gap between the two rollers. By arranging temperature-controldevices at both rollers, or, if necessary, only at one of the tworollers, the temperature of the coating medium to be transferred can beset precisely.

With the temperature-control devices described here, a so-calledexternal temperature-control of the coating medium in the transportsystem of the coating medium can be eliminated. The coating supplydevices can be of a conventional type. Obviously, it is also possible tocombine the provided arrangement of temperature-control devices withexternal temperature-control devices. Furthermore, cleaning fluids thatare to be applied to the surfaces contacting the coating medium can bepreferably heated.

The temperature control can also be performed from the outside by meansof radiators or by the supply of a gaseous temperature-control medium.Then the temperature control can be connected in a particularlyeffective way to the already metered thin films of the coating medium.

A particular advantage of the temperature control of chamber wiper 4 isthat the wiper blade cannot be deformed by fluctuating temperatures.Deformation or bowing of the wiper leads to different meterings over thewidth of the wiper, which are hereby avoided.

The mentioned device enables processing combinations for applyingdifferent application processes of coating technology in sheet-fedoffset printing presses or pure coating machines with several applicatorsystems. In this way, a dispersion coating can be coated on a dispersioncoating. The dispersion coating can be combined with gold varnish. Adispersion coating as the bottom layer can be combined with a UVcoating.

With the temperature-control devices described hererin, externaltemperature-control of the coating medium in the transport system of thecoating medium can be eliminated. The coating supply devices can be of aconventional type. Obviously, it also is possible to combine thearrangement of temperature-control devices as described herein withexternal temperature-control devices. Furthermore, cleaning fluids thatare to be applied to the surfaces contacting the coating medium can bepreferably heated.

The temperature control also can be performed from the outside by meansof radiators or by the supply of a gaseous temperature-control medium.Then the temperature control can be connected in a particularlyeffective way to the already metered thin films of the coating medium.

A particular advantage of the temperature control of chamber wiper 4 isthat the wiper blades cannot be deformed by fluctuating temperatures.Deformation or bowing of the wiper leads to different meterings over thewidth of the wiper, which are hereby avoided.

The mentioned device enables processing combinations for applyingdifferent coating applications in sheet-fed offset printing presses orpure coating machines with several applicator systems. In this way, adispersion coating can be coated on a dispersion coating. The dispersioncoating can be combined with gold varnish. A dispersion coating as thebottom layer can be combined with a UV coating. Finally, two layers ofUV coating can be applied. In the case of dispersion coating, thetemperature control is used to stabilize the coating properties. In thecase of UV coating, the temperature control, particularly throughheating, is used to improve the processing properties, e.g., of thedistribution of the coating on a surface. Cooling can be performed,e.g., for an aqueous metal pigment coating or a metal pigment printingink, because this coating or this printing ink exhibits an optimumconsistency within certain temperature ranges.

The described system can be expanded by also providing roller coatingsystems or roller lining units with an optional,temperature-controllable coating tank that is comparable to the chamberwiper 4 or the coating supply to a so-called crushing roller system,e.g., a coating knife that dips into a coating storage tank between thetwo rollers forming the crushing roller, system.

What is claimed is:
 1. A coating system for supplying a coating mediumto sheet material during sheet transfer comprising a coating mediumapplicator system including a form cylinder (2) for applying coatingmedium to sheet material and a metering system (5) for metering andtransferring a predetermined amount of coating medium to said formcylinder (2) or sheet material attached to the form cylinder (2); saidmetering system including a wiper chamber (4) having a wiper body and atleast one wiper blade for containing a quantity of coating material, ascreen roller (3) in contacting interposed relation between said wiperchamber (4) and said form cylinder (2) for receiving a metered quantityof coating medium from said wiper chamber (4) and transferring saidcoating medium directly to said form cylinder (2) or sheet materialattached to the form cylinder (2), a sensing device for detecting thetemperature of said coating medium; at least one of said wiper chamber(4) and screen roller (3) which contact the coating medium duringtransport to the sheet material having an associated heat exchanger (A;B) such that the temperature of the coating medium can be influencedduring metering or transport immediately prior to application onto thesheet material.
 2. The coating system of claim 1 in which said heatexchanger is operable for supplying heat to at least one of said wiperchamber and screen roller.
 3. The coating system of claim 1 in whichsaid heat exchanger is operable for dissipating heat from at least oneof said wiper chamber and screen roller.
 4. The coating system of claim1 including a heat exchanger is operable for supplying heat to said formcylinder.
 5. The coating system of claim 1 including a heat exchangeroperable for dissipating heat from said form cylinder.
 6. The coatingsystem of claim 1 in which said heat exchanger is located within atleast one of said wiper chamber and screen roller.
 7. The coating systemof claim 1 in which said screen roller is formed with flow channelsthrough the coating medium passes, and said heat exchanger is operablefor controlling the temperature of the medium passing through the lowchannels.
 8. The coating system of claim 1 in which said heat exchangeris located on an exterior side of said wiper chamber and screen roller.9. The coating system of claim 8 in which said heat exchanger is in theform of a radiator.
 10. The coating system of claim 8 in which said heatexchanger is a temperature-controlled air directing means.
 11. Thecoating system of claim 1 in which each of said wiper chamber and screenroller have at least one sensor for detecting the temperature of thecoating medium at each location.
 12. The coating system of claim 1 inwhich each of said wiper chamber and screen roller have at least onesensor for detecting the temperature of each of the wiper chamber andscreen roller.
 13. The coating system of claim 1 in which said wiperchamber (4) has two wipers in contacting relation to said screen roller(3).